The organic chemist has long known a method for the preparation of certain methine compounds. The preparation of a specific compound in Chemical Abstracts (CA 60 16389f Med. Chemie, Abhandl. Med. Chem. Forschungsstaltten Farbenfabriken Bayer, 7 609-28 (1963)); this compound has only been reported. [Med. Chemie, 7, 609-28(1963)]; this compound has only been reported as a medicinal compound. With the increasing requirments for better dyestuffs for polyester fabrics, as well as the necessity of finding compounds suitable as pigments for rigid plastic substrates, the search for suitable dyestuff compounds has continued in recent years with great activity.
In accordance with the invention, I have discovered methine compounds suitable for the dyeing of polyester fabrics, and particularly for the coloration or rigid plastic substrates.